netfilter: Allow xt_owner in any user namespace
Making this work is a little tricky as it really isn't kosher to change the xt_owner_match_info in a check function. Without changing xt_owner_match_info we need to know the user namespace the uids and gids are specified in. In the common case net->user_ns == current_user_ns(). Verify net->user_ns == current_user_ns() in owner_check so we can later assume it in owner_mt. In owner_check also verify that all of the uids and gids specified are in net->user_ns and that the expected min/max relationship exists between the uids and gids in xt_owner_match_info. In owner_mt get the network namespace from the outgoing socket, as this must be the same network namespace as the netfilter rules, and use that network namespace to find the user namespace the uids and gids in xt_match_owner_info are encoded in. Then convert from their encoded from into the kernel internal format for uids and gids and perform the owner match. Similar to ping_group_range, this code does not try to detect noncontiguous UID/GID ranges. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Kevin Cernekee <cernekee@chromium.org> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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